1. Field of the Invention
This invention relates to a speaker design support apparatus and a speaker design support method for supporting the designing for a speaker comprising a voice coil, a magnetic circuit, and so on.
2. Description of the Related Art
So far, the speaker has been applied to an audio system or the like. Recently, it is also applied to various devices such as a mobile phone. The mobile phone is required to be downsized and to be provided with the high performance. In order to manufacture the downsized mobile phone with high performance feature, the mobile phone makers impose many requirements (target specifications) on the speaker makers regarding the size, the sound pressure, the mode pattern, and etc. Accordingly, the speaker makers will manufacture the speaker meeting the requirements.
And now, a configuration of the speaker is explained according to FIG. 7. As shown in FIG. 7, a cylindrical magnet 73 is placed at the center of a patelliform yoke 74 with U-shaped section keeping a specific distance from a sidewall of the yoke 74, and a magnetic plate 72 is placed on this magnet 73. A bobbin 76 provided so as to be perpendicular to a diaphragm 75 of the speaker is inserted into a gap between the plate 72 and the yoke 74. A coil 71 winds around the bobbin 76. The diaphragm 75 comprises a diaphragm body 751 at the center and edge 752 on the periphery of the diaphragm body 751. The edge 752 is bonded to a frame 77. According to such configuration, a closed magnetic circuit is consisted of the magnet 73, the plate 72 and the yoke 74. When the voice electric current flows on the coil 71 wound around the bobbin 76 placed in the gap, the diaphragm 75 vibrates by the electromagnetic force.
The frame 77 is provided with a through-hole 77a to control an excursion of the diaphragm 75 under the low frequency band. An acoustic resistance member 77b covering through-hole 77a is equipped at the outside of the frame 77's back. The front side of the speaker is provided with a protector 78 to protect the diaphragm 75 and etc. Besides, the protector 78 is provided with a plurality of through-holes.
The speaker is provided with the voice coil 71; the magnetic circuit comprising the plate 72, the magnet 73 and the yoke 74; and the diaphragm 75, as mentioned above. Therefore, It is very important for the speaker designing to design the voice coil 71, the magnetic circuit, and the diaphragm 75.
A designer manufactures a speaker by way of trial after designing the voice coil 71, the magnetic circuit, and the diaphragm 75. And, the designer evaluates whether the trail speaker meets the above-mentioned requirements regarding the sound pressure, the mode pattern, and the like.
If it fills the requirements, the trial speaker is shipped as a sample to the above mobile phone makers. If not, the designer goes back to the steps for designing the voice coil, the magnetic circuit, and the diaphragm.
The characteristic of a voice coil 71 depends on a coil diameter, a material and a diameter of a wire rod, a winding pattern, and the number of windings. For this reason, when the designer designs the voice coil 71 with a given characteristic, it is necessary to properly determine a coil diameter, a material and a diameter of a wire rod, a winding pattern of the wire rod, and the number of windings. However, there are likely two or more examples of respective items necessary for designing the voice coil 71 such as the coil diameter, the material and the diameter of the wire rod, and the like. And, many cases can be considered as the combination of the items. Accordingly, it is not easy to design the voice coil 71 with the specific characteristic and hard to finish the design in a short time.
The magnetic circuit has a different characteristic such as the magnetic flux density and the like depending on respective materials and sizes of the plate 72, the magnet 73, and the yoke 74 composing the magnetic circuit. The designer has to properly determine a material and a size of each component member of the magnetic circuit. Therefore, it is difficult to finish the design of the magnetic circuit in a short time. Similarly, it is also difficult to finish the design of the diaphragm in a short time.
In addition, the speaker characteristic is determined according to the multiplex relation among respective shapes of the voice coil, the magnetic circuit, and the diaphragm. Accordingly, even if it is completed to design the voice coil, the magnetic circuit and the diaphragm respectively, the characteristic of the speaker such as the sound pressure is not determined before studying the mutual relations of the voice coil, the magnetic circuit, and the diaphragm. When the speaker is assembled by combining the voice coil, the magnetic circuit, and the diaphragm that have been manufactured experimentally based on the design, the assembled speaker naturally meets the requirements imposed by the mobile phone maker, but seldom. If the speaker meets no requirements, it is necessary to redesign the voice coil, the magnetic circuit and the diaphragm in order to assemble another speaker. It is general that the speaker as trial product is made up plural times. The design of the speaker in the past needs a very long time, e.g. a few weeks.
The designers design a voice coil, a magnetic circuit and a diaphragm according to their own experience. When an unskilled person designs a speaker, the unskilled person needs more time to design the speaker than a skilled person or cannot design the speaker according to the circumstance.